test_runner: support coverage of unnamed functions

This commit updates the code coverage logic to skip the first
function in a file (which does not correspond to an actual
function) instead of skipping all functions without a name.
PR-URL: #47652
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: cjihrig

lib/internal/test_runner/coverage.js

@@ -155,7 +155,7 @@ class TestCoverage {
 });
 
 for(letj=0;j<functions.length;++j){
-const{functionName,isBlockCoverage, ranges }=functions[j];
+const{ isBlockCoverage, ranges }=functions[j];
 
 for(letk=0;k<ranges.length;++k){
 constrange=ranges[k];
@@ -172,7 +172,7 @@ class TestCoverage {
 }
 }
 
-if(functionName.length>0&&ranges.length>0){
+if(j>0&&ranges.length>0){
 constrange=ranges[0];
 
 if(range.count!==0||range.ignoredLines===range.lines.length){

test/fixtures/test-runner/coverage.js

@@ -29,7 +29,7 @@ if (false) {
 require('./invalid-tap.js');
 }
 
-test('a test',functiontestHandler(){
+test('a test',()=>{
 constuncalled=()=>{};
 
 functionfnWithControlFlow(val){